What was the order of operations when it came to installing the facing stones on the large pyramids of the Fourth Dynasty? Were they just ornamental or did they serve a larger purpose in the engineering of the pyramids themselves? Was there a difference between how the rare instances of granite facing stones were installed and the Tura limestone facing blocks still visible on parts of the pyramids today? Join us as we probe the thoughts of a man who spends more time systematically and scientifically studying the large pyramids than any other person alive, Jean-Pierre Houdin.

Em Hotep: Hi Jean-Pierre. A few weeks ago, you posted the following comments on Em Hotep BBS about Menkaure’s pyramid:

I hope I’ll have some time in a few days to tell you something about granite facing blocks and Turah limestone facing blocks…There is a huge difference in the way of setting…which has been skipped by all Egyptologists talking about pyramid construction… Stay tuned

First of all, before talking about the different ways of setting granite and limestone facing blocks, could you summarize for us what Egyptologists put forward regarding the facing of the pyramids?

Jean-Pierre Houdin: Keith, thank you for coming back to me in the form of an interview for Em Hotep as that will be easier for me. Looking at a picture of Menkaure’s pyramid posted in the Em Hotep BBS Facebook Group, I thought that it was a nice opportunity for me to give my explanation about the casing stones of the Egyptian large smooth pyramids and the different methods of setting depending on the material (Tura limestone / Granite) and the support.

When you look at what Egyptologists wrote about the facing of the pyramids, you will find many “academic” propositions, although none among the most widely proposed is plausible at closer look.

Based on the Herodotus text, there are those who say that the facing blocks were added to the layers from top to bottom; I won’t bother with this because from a masonry perspective it is nonsense, a builder knows this would be technically impossible.

Still based on the Herodotus text, there are those who say that the blocks were set in place as “cubes” and that cutting and smoothing, following the slope, were done at the end of the construction, from top to bottom. Although this could have been technically feasible, this is certainly the worst idea because the work would have been very hard – you will understand why later – and would have concerned 84,000 square meters in the case of Khufu’s pyramid. Because of the length of the layers in the upper levels, the number of workers would have been very low at the beginning, increasing only slowly while the facing work came down. Doing it this way would have added ten years of work to the construction, not to mention that the shape of the pyramid would have rapidly begun to twist.

At last, in the same concept, there are those who think that only extra stock, or, material, was left at the front faces for the setting and that it was smoothed later on. That’s simply impossible because you don’t have any support for the workers to stand on and you still have the same pyramid surface area to smooth as above.

That said, many Egyptologists (read annexes below) agree about a simple fact: the facing stones (Tura limestone), already carefully smoothed, were certainly the first ones to be set in place, layer after layer, but nobody is able to explain WHY and HOW.

Em Hotep:In fact, when you look at all these pyramids, almost all have a full Tura limestone casing, so there must be a reason.

Jean-Pierre Houdin: Yes, but I first have to explain WHY the Egyptians left aside the step pyramid model (ex: Saqqara) to build the large smooth pyramids.

Answer: The choice of the Tura limestone for the facing blocks, which represents 99%+ of all surfaces built.

From the beginning of stone building (Saqqara step pyramid and mastabas) and with time, experiments and knowledge, Egyptians came to the conclusion that they would be able to build perfect large smooth pyramids thanks to the qualities of the Tura limestone (a material which they already used for the facing). The fact is that this limestone is almost white, very dense (density 2.5) and with a thin granulation, so it is very suitable for the facing of a pyramid. On top of that, this limestone is SOFT while it is still in strata at the quarry, whilst it becomes very hard quickly after being quarried out. As the main cutting tools were copper chisels, the most logical step was to completely cut and smooth the facing blocks at the quarry directly after extraction; doing this the stonecutters benefited from the softness of the limestone and reduced the wear on their tools.

A modern Tura limestone quarry where blocks are still completely dressed (Source: Wikipedia Commons)

Technically, regarding lengths and levels, Egyptians had no precision tools available to check long distances like the lower layers of a pyramid, the most important layers to determine its future perfect shape. So, by extending the work at the quarry, Egyptians imagined a smart solution for the whole facing which resolved the accuracy problem: to “prefab” there, block by block, the four faces of each course. The height of each layer was determined by the height of each strata from which the blocks were cut. Each block of a same layer was cut and accurately dressed concomitantly with its two adjoining blocks (right and left); then all blocks of a same layer and face were criss-crossed to check the slope and the height. After which and while still at the quarry, the “prefab” blocks were positioned in order to “pre-build” a full row of a facing and quarry marks were added, bearing the laying information for the masons who worked at the pyramid; in this way the ancient Egyptians had practically invented the bar-code system of logistics used by modern builders today. Finally, the blocks were loaded on sledges, like we do with our pallets, and were sent to the building site, the Egyptians having also set up an amazing supply chain!

A facing block on a sledge, ancestors of our pallets, with its wooden protection on the front face (Source: Dassault Systemes/Jean-Pierre Houdin)

Although the blocks were protected during shipping, many were damaged during transportation and needed some repairing before final setting. The Tura limestone blocks could be mended with copper chisels: precise holes were carved around the damage and Tura limestone plugs were inserted as repair patches. Many restorations are still visible in the facing blocks of the Bent pyramid at Dashur. In addition, one can see that some of the patches were inserted from the top, proving that these restorations were carried before the block of the layer immediately above was laid on, and, as a consequence, that final smoothing was done as the pyramid was rising up rather than after the blocks were set in place.

Different kinds of patches and some visible at the Bent pyramid (Sources: Dieter Arnold and Jean-Pierre Houdin)

Em Hotep:So why have Egyptologists come short of an explanation?

Jean-Pierre Houdin: A fact: Large smooth pyramids of the Fourth Dynasty were built by successive horizontal layers and this was fundamental for the building processes.

Blinded by the “Pensée Unique”, based on the wrong paradigm that the pyramids were built from the OUTSIDE, they could not imagine any plausible explanation on HOW these stones were set in place although many are sure they were set from the inside. They all are unable to give this explanation because they missed this point: the setting in place of the facing stones is the MAIN condition which is behind the conception of the construction processes; so if one is unable to explain the setting of the facing blocks, one is unable to explain the construction of the pyramids.

No one has ever been able to give a plausible explanation for a very simple reason: no one has ever imagined that these pyramids were built INSIDE-OUT, which means that all materials are brought inside the perimeter of the pyramid before the setting, in this order: the casing stone at first, then the backing stones and the rough blocks for the filling last, this process repeated layer after layer from base up to top. Setting the Tura limestone blocks inside-out was imperative because the workers could simply not stand on the outside part of the blocks, as these were already pre-cut following the slope—there would have been nowhere to stand. On the contrary, they had all the support needed to work from the inside.

The Tura limestone casing stones are set from the inside and the facing is done as the pyramid rises (Source: Dassault Systemes/Jean-Pierre Houdin)

Cherry on the cake, this technique allowed a constant control of the shape of the pyramid during the whole construction because the faces, edges, diagonals and axis were free of any obstructing element. Thus, any slight correction was easy to perform.

The edges are free and can be easily checked (Source: Dassault Systemes/Jean-Pierre Houdin)

The only problem was to be able to bring the blocks inside the perimeter layer by layer, this from base to top.

Enter: for large smooth pyramids, an external ramp up the one third of the height (2/3 of the volume), and an internal ramp for the last 2 thirds (1/3 of the volume). That’s all…simple and logical!

You know the theory…

Otherwise, instead of an internal ramp, the smaller pyramids (around 60m high and less) built after Khafre’s pyramid and during the 5th, 6th and following Dynasties were built thanks to a “construction gap” which was filled at the end of the construction with the same materials as the body. The pyramids of Sahura and Neferefra in Abusir each show the remains of a “construction gap”.

In a square based pyramidal volume, there is a constant: at one third of the height, there is already 2/3 of the volume, no matter the slope. (Source: Jean-Pierre Houdin)

Em Hotep:Now, you gave us your explanation for the Tura limestone, but why is there a “huge difference” in the methods of setting for the less than 1% remaining facing made of granite blocks?

Jean-Pierre Houdin: There are only two known examples of the use of granite blocks for the facing of a pyramid and these are both on the Giza Plateau: the pyramids of Khafre and Menkaure, and strangely their setting in place were done following two different processes.

In order of construction, Khafre’s pyramid came first (after Khufu’s pyramid and Djedefre’s pyramid) and the architects took advantage of the topography to build a slightly smaller pyramid next to Khufu’s pyramid. Nevertheless, this pyramid seems to be as big as its older sister because the geometers implanted it fifteen meters higher on the Plateau. Moreover, a former construction ramp (the ramp of the port) used for Khufu’s pyramid was recycled as the base for the causeway linking Khafre’s Valley Temple to the Upper Temple. As a consequence, and due to the slope, the pyramid was implanted between contour lines 65 and 80, straddling over contour lines 70 and 75. There is a big difference of level between East and West, which led to the bedrock of local limestone around to be largely quarried for the construction, particularly towards North and West.

Khafre’s pyramid straddling on contour lines 70 and 75 (the North is on top) Source: Albert Ranson/Jean-Pierre Houdin

Khafre’s pyramid is directly built in a large quarry (Source: Jean-Pierre Houdin)

By the way, the base of the pyramid was carved in steps for up to 10 meters in height directly in the bedrock on the Northwestern edge. As the bedrock was at lower levels in the other edges and all along the four faces due to the slope, huge blocks of limestone were cut directly inside the perimeter of the pyramid and were dragged forwards in order to create steps all around and up to 8 meters in height.

Thus, because of the size of these limestone blocks, it was becoming impossible to set in place the granite facing blocks from the inside, so these rather small blocks, already precisely dressed and smoothed, were pushed from the outside against the steps, the voids being filled with mortar.

Although there is no historical evidence of the number of rows built with these kind of blocks, it seems obvious, when looking at the base of the pyramid, that some five or six rows were made with this material; some Tura limestone blocks must also have been set in place the same way in a few areas like the Northwestern edge. For the remaining part of the pyramid, above the granite and up to the top, the inside-out technique was used for all the facing blocks in Tura limestone.

The granite blocks at the base did not have any role regarding the structure, such as controlling the overall shape of the pyramid, like the Tura limestone blocks did, they were just a simple facing.

Em Hotep:Ok, I understand now that the topography had a great influence for Khafre’s pyramid, but for what reason did the Egyptians change the process for the setting of the granite blocks of Menkaure’s pyramid?

Jean-Pierre Houdin: You have first to think that Menkaure’s pyramid is much smaller than its two sisters: a square base of a little more than 100m for a 65m height with a volume about only 1/10th of Khufu’s pyramid. When you look again at the topography diagram, you see that Menkaure’s pyramid is implanted between the contour lines 70 and 75, so the difference of level is much smaller than in Khafre’s case. The consequence is that no step was carved directly into the bedrock to support the facing blocks.

Menkaure’s pyramid implanted between contour lines 70 and 75 (the North is on top) Source: Albert Ranson/Jean-Pierre Houdin

You will also notice the “wave” drawn by the contours lines on the Northeast side of the pyramid. This topography detail played an important role for the implantation of the pyramid, particularly regarding the external ramp component of the construction processes (the same kind of topography detail played also a role for Khafre’s pyramid, but in a lesser extend).

Menkaure’s pyramid implanted on a less sloping part of the Plateau (Source: Wikipedia Commons)

It seems probable that the Egyptians encountered some trouble with the granite blocks of Khafre’s pyramid. Whether they came already dressed from the Aswan quarries (the same technique as with the Tura limestone facing blocks) and many were damaged during transportation, or whether they were only finally dressed on the building site just before the setting, many were damaged during the construction of the pyramid. For whatever reason, it matters little but the result was that the Egyptians were unable to repair these blocks because they had no tools hard enough to make precisely cut holes and to insert plugs; they had to reshape damaged blocks, something which was still possible because these blocks were just a simple facing and very close to the ground.

During the design of Menkaure’s pyramid, the architects chose to do the facing, for the first sixteen layers, with granite blocks. They went back to the INSIDE-OUT technique, with the facing blocks embedded in the structure like they did with the Tura limestone blocks. To avoid damaging the blocks before the end of the construction, the granite blocks were sent, from the Aswan quarries, with extra stock kept on the front face, with even bulges at the bottom for the use of levers during setting.

The granite blocks for the facing of Menkaure’s pyramid are longer to be structurally embedded (Source: Mathias Glad)

Extra stock was kept on the front face (Source: Mathias Glad)

Bulges at the bottom of the granite blocks for the use of levers (Source: Mathias Glad)

So the first sixteen layers were built INSIDE-OUT, like the Tura limestone blocks for the layers above, these last ones being already smoothed as usual. The smoothing of the granite blocks was planned for the end of the construction, using wooden scaffolds since this work was limited to the lower part, easily accessible from ground.

Now, what happened, as most of the smoothing was never done?

It seems that the work had partly begun as normal as the bulges of the lower courses were erased.

The bulges are erased on the lower part (Source: Mathias Glad)

The finishing work must have been stopped by one unexpected event: the death of King Menkaure.

That left practically no choice for the builders but to only smooth the granite blocks around the entrance while the funeral processes were carried out at the Valley Temple, with only around two months left for that work.

That seems strange because the entrance of the descending corridor was de facto clearly spotted on the pyramid’s North face, but who knows?

I would be very pleased to get an explanation from Egyptologists about this last detail.

Menkaure’s pyramid entrance is clearly spotted on the North face (Source: Mathias Glad)

Em Hotep:Thank you Jean-Pierre for this long explanation which seems to be supported by the evidence on site. As a conclusion, could you tell us what are your projects for the coming months; we all know that your ultimate desire would be to carry out a survey on Khufu’s pyramid. Do you have something in preparation?

Jean-Pierre Houdin: I will give you a short summary about our attempts to carry out a survey on Khufu’s pyramid:

In 2005, I was very close to being able to do a survey, and five to seven non-destructive techniques were available, with all the teams ready to go. All the data (among them CVs and copies of passports) required by the SCA for each member of the five teams selected (around 50 members) were filled in the SCA application file. All the survey processes were clearly detailed and a plan was set. Unfortunately, I never had the chance to apply, “someone” being opposed for strange reasons.

Should this authorization had been given, today we would be sure that my theory is the right one (or not).

On March 30 – 2007, we did a first press conference (Khufu Revealed), Dassault Systèmes and I, at la Géode, which drew a very huge audience around the world. A few days later, with the “Team”, we did a first trip to Cairo to meet “someone” at the SCA. At the end, we were told to come back for a second trip, to present the 3D animation to “foreign experts”. At that time, we thought that this authorization would come quickly, but “someone” was again against us.

In 2008, we thought that the three documentaries filmed about the theory (a French one, an American one and a Japanese one) would help to make the theory worth a survey. An half an hour visit by Dr Bob Brier in the Northeastern edge had an impressive result: the re-discovery of a room built at the exact spot of a rotation space of the internal ramp. Since this, I received tens of thousands of e-mails from people around the world who congratulate us for the work done and who support the theory. And this still valid today. Although some people told to “someone” to let us make an infrared survey, something totally non-destructive as we would stand at 200 m or more from the pyramid, “someone” didn’t care about it.

On January 27 – 2011, we did a second press conference, Dassault Systèmes and I, at la Géode (Khufu Reborn) to reveal the probable existence of two unknown antechambers, whilst the theory was upgraded thanks to the room discovered by Bob. The news went all around the world once again but the same day, the revolution in Egypt began and is evidently not finished.

To the contrary, “someone” seems to be out of the game.

That said we didn’t waste any time in between; with Alain Dugousset, a Dassault Systèmes CATIA specialist, we went back in the past, before Khufu’s era. We have modeled the Red pyramid in Dashur with all the construction processes included. And let me tell you that the Bent pyramid is not far behind, as the construction processes of this pyramid are a mixture of the processes used in building the Red and Khufu’s (and Khafre’s) pyramids. The explanation of the construction of the Four Big Pyramids should be “wrapped up” in the not-too-distant future.

In parallel, I’ve discovered a new non-destructive technique which will be used side by side with the infrared technique, both techniques being complementary. We are now working with people in Cairo to set up a new international team including a well-known Egyptian Faculty. It’s once again a challenge because of the situation in Egypt, but I’m confident that Time is still on our side.

At last, I’m right now preparing a paper about the Sphinx. After the 2011 press conference, I was stunned that nobody noticed that the Sphinx was modeled in the 3D animation, carved while Khufu’s pyramid was in construction. The “Fly-over” at the end of the presentation (and visible on the www.3ds.com/khufu website) didn’t catch the attention of anyone, although this is something which should have led to lots of questions. I’ll also explain WHY there are strong rain erosion marks on the side walls of the Sphinx quarry, rain erosion following the construction of Khafre’s pyramid, not 10.000 years ago.

Stay tuned…

Annexes: Abstracts from Egyptology Books

From Peter Tompkins’s book: Secret of the Great Pyramid

Page 228

Petrie believes the masons finished and laid the casing and some of the core masonry, course by course, on the ground, before raising them. He found horizontal lines carved on the casing stones and on the core stones showing just how they were to be fitted. He believes that skilled masons planned all the work throughout the year and that a flood time gangs of unskilled workmen raised the finished stones to their indicated positions.

Petrie says the casing stones were dressed very fine picking or adzing and were moved into position from the inside, whereas the core was filled in afterwards.

Pages 228/229

Maragioglio and Rinaldi, two Italian scholars who recently made extensive measurements of the pyramids of Giza which they incorporated into four carefully illustrated quarto volumes entitled l’Architectura delle Pyramidi Menefite, agree that the casing and the nucleus were built up at the same time; they think the casing blocks were slid into place by means of a thin layer or very liquid mortar that served as a lubricant as well as a filler and binder; they also think the casing blocks were levered into position from the back and sides so as not to show marks or chips in the front.

Page 229

In support of Petrie, I.E.S. Edwards points out that because the lowest course of casing stones lies on the smooth pavement of Tura limestone which project a couple of feet beyond the Pyramid base, it would have been impossible to lay the casing stones from the outer side without damaging the fringe of the pavement which was to remain exposed; nor could they have been dressed after being put in position without damaging the pavement.

The fact that some of the limestone slabs of the foundation pavement are seen to be laid beneath the nucleus blocks also indicates the nucleus was filled in after the casing blocks have been placed in position.

Petrie believes the casing blocks were placed side by side on the ground and worked so that the back, sides and bottom would fit perfectly when put in place. The only thing left to do on the spot would have been the levelling of the upper face.

Pages 229/230/231

In any case, the arrangement of casing blocks must have been worked out in detail well in advance of placement so as to assure a variance in the width and height of the backing stones from level to level, so as to prevent the vertical joints from coinciding.

All the stones presently visible in the Pyramid are backing stones specially cut to dovetail and fit behind the outer casing. They are dressed and squared, but made with fossilized limestone instead of the pure white.

Behind them the nucleus consists of less well-dressed and roughly faced blocks of greatly varying

sizes, for easier construction, and to ensure that break joints did not coincide in either sense? They are held together by a mortar composed of sand, lime and crushed red pottery, which gives it a slightly pinkish color.

From Dieter Arnold’s book : Building in Egypt – Pharaonic Stone Masonry

Page 119

Often, each course has a different height, even in pyramid casing, suggesting that blocks of similar height had been arranged in the storage area to permit speedy transport and setting in the walls. Without this preparation, builders would have received blocks of different dimensions, which would have required additional dressing and resulted in a waste of material.

Page 132

Normally, building stones were set with extra stock at the front faces. There are instances, however, where blocks were already dressed down before setting, and we do not always understand under what conditions this happened.

Page 169

There is no doubt that the casing, backing and packing stones were treated as a structural unit to be built simultaneously.

The casing stones at the top of the pyramid are much smaller – about 1 cubit thick (c.50 cm/20 in) – than the casing stones which survive at the bottom of Khufu’s pyramid and those of his queens. Their outsides are often staggered by a few millimeters rather than flush. This might suggest that at this level, the outer slope was cut into the blocks before they were laid, due to reduced working space.

I watched a documentary about Dejefre and within the content, they discussed the use of granite. This took me to Menkaure’s pyramid, which the documentary said was built after and that this brother probably used the granite because his older brother Dejefre did (perhaps some was left over or extras? used to put the bottom skirt around Menkaure’s?).

Soooo … I began looking at Menkare’s pyramid and wondered why the bottom stones are rounded and have those projections (now I know they were for levers! THANK YOU JP!) As for the use of granite on the outside of this pyramid – I think it was preference or more likely, it was that by the time this pyramid was being built, granite had become more readily available and of course, since they learned how to move the heavy stone with their construction of the other pyramids, they had more applicability with this type of stone. I hope that makes sense!

However, and I think I may know this already – with the stones on Menkaure’s pyramid being more rounded, is this why they look well, like they have deeper or more space between them? I would guess that this visual space would have been reduced greatly if those rounded stones had time to be brought into a more level plane?

Now, more questions …. Can you explain more about the construction gap? Do you mean an actual gap in the building process or an actual gap in the blocks through which they ??? I’m confused.

About the stone cat … I noticed the extreme weathering and more in the flyover. But I have spent little time researching the ancient weather and rains. I assumed it was NOT 10,000 years old, as some say, but could not figure out the rest because I have not given the time to the study of how water would flow over the whole area. I’m gonna guess Jean Pierre did not lack in this department and I’m eager to read his work.

Now, who has the stones, the land and the willingness to fund JP to create another HUGE pyramid to show us how it’s done!

The conventional explanation is that you define a slope by a seked, or ratio of step to rise. So you get out your cubit measuring rod, and measure one cubit rise, and 5 palms two digits step, put marks, and cut the limestone to fit.

However that’s not particularly accurate. You can also do it like this. Cut the block to a rectangle as close to one cubit in height as you can get (but it won’t be perfect). Draw a vertical line where you want the slope to end (use a plumbline to get an exactly vertical line). Construct a square round that line (use dividers, set them to the height of the line, construct two lines, then bisect them, then make two more vertical lines using the plumb line).

Now swing out the diagonal of the 1:2 rectangle you have constructed. This gives you a “golden rectangle”. Then take the diagonal of the golden rectangle, and swing up. The result is a line in the ratio 1 : root phi.

So even if our original measurement of 1 cubit was a bit out, the slope will still be very near perfect, because we’ve constructed it geometrically. So the resulting pyramid is a perfect golden triangle, with the sides in the ratio 1 : root phi : phi.

[...] published discussion regarding the practical challenges faced by the Ancient Egyptians when installing these casing stones, as opposed to the mathematical, metrological and symbolic issues that I have discussed above. [...]